diff -Naur syslinux-6.03/mk/com32.mk syslinux-6.03-lunar/mk/com32.mk
--- syslinux-6.03/mk/com32.mk	2014-10-06 17:27:44.000000000 +0100
+++ syslinux-6.03-lunar/mk/com32.mk	2020-08-05 12:30:53.321063508 +0100
@@ -47,6 +47,7 @@
 GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
 GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
 GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
+GCCOPT += $(call gcc_ok,-fcommon)
 
 ifndef EFI_BUILD
 GCCOPT += -mregparm=3 -DREGPARM=3
diff -Naur syslinux-6.03/mk/efi.mk syslinux-6.03-lunar/mk/efi.mk
--- syslinux-6.03/mk/efi.mk	2014-10-06 17:27:44.000000000 +0100
+++ syslinux-6.03-lunar/mk/efi.mk	2020-08-05 12:31:35.897730635 +0100
@@ -8,6 +8,7 @@
 # gnuefi sets up architecture specifics in ia32 or x86_64 sub directories
 # set up the LIBDIR and EFIINC for building for the appropriate architecture
 GCCOPT := $(call gcc_ok,-fno-stack-protector,)
+GCCOPT += $(call gcc_ok,-fcommon)
 EFIINC = $(objdir)/include/efi
 LIBDIR  = $(objdir)/lib
 
diff -Naur syslinux-6.03/mk/elf.mk syslinux-6.03-lunar/mk/elf.mk
--- syslinux-6.03/mk/elf.mk	2014-10-06 17:27:44.000000000 +0100
+++ syslinux-6.03-lunar/mk/elf.mk	2020-08-05 12:30:42.381063392 +0100
@@ -42,6 +42,7 @@
 GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
 GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
 GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
+GCCOPT += $(call gcc_ok,-fcommon)
 
 com32 = $(topdir)/com32
 core = $(topdir)/core
diff -Naur syslinux-6.03/mk/embedded.mk syslinux-6.03-lunar/mk/embedded.mk
--- syslinux-6.03/mk/embedded.mk	2014-10-06 17:27:44.000000000 +0100
+++ syslinux-6.03-lunar/mk/embedded.mk	2020-08-05 12:30:29.224396585 +0100
@@ -52,6 +52,7 @@
 GCCOPT    += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
 GCCOPT    += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
 GCCOPT    += $(call gcc_ok,-fvisibility=hidden)
+GCCOPT    += $(call gcc_ok,-fcommon)
 
 LIBGCC    := $(shell $(CC) $(GCCOPT) --print-libgcc)
 
diff -Naur syslinux-6.03/mk/lib.mk syslinux-6.03-lunar/mk/lib.mk
--- syslinux-6.03/mk/lib.mk	2014-10-06 17:27:44.000000000 +0100
+++ syslinux-6.03-lunar/mk/lib.mk	2020-08-05 12:30:10.057729709 +0100
@@ -28,6 +28,7 @@
 GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
 GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
 GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
+GCCOPT += $(call gcc_ok,-fcommon)
 
 INCLUDE	= -I$(SRC)
 STRIP	= strip --strip-all -R .comment -R .note